BLADE-SHAPED CUTTING INSERT AND CUTTING TOOL THEREFOR

Abstract

A blade-shaped cutting insert has opposing first and second insert side surfaces with a peripheral surface extending therebetween, and a first cutting portion having a first primary cutting edge extending between the first and second insert side surfaces, defining a maximum insert width of the cutting insert. The peripheral surface includes an upper surface and first and second diverging flank surfaces bisected by a first plane transverse to the upper surface. The cutting insert has a maximum insert length measured perpendicular to the first plane which is more than sixteen times greater than the maximum insert width, and a maximum insert height measured parallel to the first plane which is more than ten times greater than the maximum insert width. The cutting insert is removably secured in an insert receiving pocket of a tool holder, which is defined by an upper clamping jaw and a lower clamping jaw.

Claims

1. A blade-shaped cutting insert (20), comprising: opposing first and second insert side surfaces (22a, 22b) with a peripheral surface (24) extending therebetween; and a first cutting portion (34a) having a first primary cutting edge (36a) extending between the first and second insert side surfaces (22a, 22b), defining a maximum insert width (W.sub.MAX) of the cutting insert (20), the peripheral surface (24) including first and second diverging flank surfaces (26a, 26b) and an upper surface (28), the first and second diverging flank surfaces (26a, 26b) bisected by a first plane (P1) transverse to the upper surface (28), wherein: the cutting insert (20) has a maximum insert length (L.sub.MAX) measured perpendicular to the first plane (P1), and a maximum insert height (H.sub.MAX) measured parallel to the first plane (P1), the maximum insert length (L.sub.MAX) is more than sixteen times greater than the maximum insert width (W.sub.MAX), and the maximum insert height (H.sub.MAX) is more than ten times greater than the maximum insert width (W.sub.MAX).

2. The cutting insert (20) according to claim 1, wherein: the first primary cutting edge (36a) is formed at the intersection of a first rake surface (38a) and a first relief surface (40a), the first rake surface (38a) is disposed on the upper surface (28), and the first relief surface (40a) is spaced apart from the first flank surface (26a) by a first lower surface (42a).

3. The cutting insert (20) according to claim 2, wherein the first lower surface (42a) forms an obtuse external fourth angle (4) with the first flank surface (26a).

4. The cutting insert (20) according to claim 2, wherein in a cross-section taken in a fifth plane (P5) parallel to the first plane (P1), the first lower surface (42a) is V-shaped.

5. The cutting insert (20) according to claim 1, wherein the cutting insert (20) exhibits mirror symmetry about the first plane (P1), and includes a second cutting portion (34b) having a second primary cutting edge (36b).

6. The cutting insert (20) according to claim 5, wherein the maximum insert length (L.sub.MAX) is measured between the first and second primary cutting edges (36a, 36b).

7. The cutting insert (20) according to claim 1, wherein in cross-sections taken in second and third planes (P2, P3) transverse to the first plane (P1), the first and second flank surfaces (26a, 26b) are respectively V-shaped.

8. A cutting tool (48) comprising: a tool holder (50) having an insert receiving pocket (52) that opens out to a forward end (56) of the tool holder (50), the insert receiving pocket defined by an upper clamping jaw (58) and a lower clamping jaw (60); and the cutting insert (20) in accordance with claim 1 removably secured in the insert receiving pocket (52) of the tool holder (50) with the first primary cutting edge (36a) being operative.

9. The cutting tool (48) according to claim 8, wherein the cutting tool (48) has a cutting depth (DC) greater than half the maximum insert length (L.sub.MAX).

10. The cutting tool (48) according to claim 8, wherein the upper clamping jaw (58) is resiliently displaceable relative to the lower clamping jaw (60).

11. The cutting tool (48) according to claim 8, wherein: the first primary cutting edge (36a) has first and second lateral end points (N1, N2) contained in opposing first and second circular sides (S.sub.D1, S.sub.D2), respectively, of an imaginary disc (DI), the imaginary disc (DI) has a central disc axis (A1) containing at least one of the first and second lateral end points (N1, N2), a first diameter (d1) equal to the maximum insert length (L.sub.MAX) and a thickness equal to the maximum insert width (W.sub.MAX), and first and second imaginary lines (L1, L2) parallel to the central disc axis (A1) and extending laterally outwardly from any respective points on the first and second circular sides (S.sub.D1, S.sub.D2), do not intersect any portion of the tool holder (50).

12. The cutting tool (48) according to claim 11, wherein a third imaginary line (L3) parallel to the central disc axis (A1) and extending laterally inwardly from a point on the first or second circular side (SD1, SD2) intersects a front support portion (66) of the lower clamping jaw (60).

13. The cutting tool (48) according to claim 11, wherein: the central disc axis (A1) contains the center point (NC) of an imaginary circle (C) coplanar with one of the first and second circular sides (SD1, SD2), the imaginary circle (C) has a second diameter (d2) greater than the maximum insert length (L.sub.MAX) and less than twice the maximum insert length (L.sub.MAX), and a first arc portion (RC) of the imaginary circle (C) intersects a lateral support portion (78) of the lower clamping jaw (60).

14. The cutting tool (48) according to claim 11, wherein: the upper clamping jaw (58) has a clamping surface (82), and the clamping surface (82) is in contact with a fastening portion (84) of the cutting insert's upper surface (28).

15. The cutting tool (48) according to claim 14, wherein: a rear non-abutting portion (86) of the peripheral surface (24) which is not associated with the first primary cutting edge (36a) circumferentially extends from the fastening portion (84) to the second flank surface (26b), and the entire rear non-abutting portion (86) makes no contact with the tool holder (50).

16. The cutting tool (48) according to claim 8, wherein: in a side view of the tool holder (50), the insert receiving pocket (52) includes first and second diverging abutment surfaces (64a, 64b) bisected by a vertical pocket plane (PV), and a portion of the cutting insert's first flank surface (26a) is in contact with the first abutment surface (64a) and a portion of the second flank surface (26b) is in contact with the second abutment surface (64b).

17. The cutting tool (48) according to claim 16, wherein the first and second abutment surfaces (64a, 64b) are disposed on the lower clamping jaw (60).

18. The cutting tool (48) according to claim 16, wherein: the lower clamping jaw (60) has a lateral support portion (78) comprising a lateral support surface (80); and one of first and second insert side surfaces (22a, 22b) is in contact with the lateral support surface (80)

19. The cutting tool (48) according to claim 18, wherein: the first abutment surface (64a) forms an acute external tenth angle (10) with the lateral support surface (80), and the second abutment surface (64b) forms an acute external eleventh angle (11) with the lateral support surface (80).

20. The cutting tool (48) according to claim 8, wherein: the lower clamping jaw (60) has opposing first and second lower jaw side surfaces (70a, 70b) defining a lower jaw thickness (T), and the lower jaw thickness (T) is more than twice the maximum insert width (W.sub.MAX) and less than five times the maximum insert width (W.sub.MAX).

21. The cutting tool (48) according to claim 20, wherein the maximum insert width (W.sub.MAX) is less than 1.5 mm.

22. The cutting tool (48) according to claim 16, wherein: the first primary cutting edge (36a) is formed at the intersection of a first rake surface (38a) and a first relief surface (40a), the first rake surface (38a) is disposed on the upper surface (28), and the first relief surface (40a) is spaced apart from the first flank surface (26a) by a first lower surface (42a).

23. The cutting tool (48) according to claim 22, wherein the first lower surface (42a) is in contact with a front support surface (68) on a front support portion (66) of the lower clamping jaw (60).

24. The cutting tool (48) according to claim 23, wherein: in a cross-section taken in a fifth plane (P5) parallel to the first plane (P1), the first lower surface (42a) is V-shaped, and the front support surface (68) is correspondingly V-shaped.

25. The cutting tool (48) according to claim 23, wherein: the lower clamping jaw (60) is divided into a front lower jaw (72) and a rear lower jaw (74) by a lower slot (76), the front support portion (66) is disposed on the front lower jaw (72), and the second abutment surface (64b) is disposed on the rear lower jaw (74).

26. A blade-shaped cutting insert (20), comprising: opposing first and second insert side surfaces (22a, 22b) with a peripheral surface (24) extending therebetween; and a first cutting portion (34a) having a first primary cutting edge (36a) extending between the first and second insert side surfaces (22a, 22b), defining a maximum insert width (W.sub.MAX) of the cutting insert (20), the peripheral surface (24) including first and second diverging flank surfaces (26a, 26b) and an upper surface (28), the first and second diverging flank surfaces (26a, 26b) bisected by a first plane (P1) transverse to the upper surface (28), wherein: the cutting insert (20) has a maximum insert length (L.sub.MAX) measured perpendicular to the first plane (P1), and a maximum insert height (H.sub.MAX) measured parallel to the first plane (P1), the maximum insert length (L.sub.MAX) is at least twelve times greater than the maximum insert width (WMAX), and the maximum insert height (H.sub.MAX) is at least eight times greater than the maximum insert width (W.sub.MAX), and wherein: the maximum insert width (W.sub.MAX) is less than 1.5 mm.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0030] For a better understanding, the invention will now be described, by way of example only, with reference to the accompanying drawings in which chain-dash lines represent cut-off boundaries for partial views of a member and in which:

[0031] FIG. 1 is a perspective view of a cutting insert in accordance with some embodiments of the present invention;

[0032] FIG. 2a is a side view of the cutting insert shown in FIG. 1;

[0033] FIG. 2b is a top view of the cutting insert shown in FIG. 1;

[0034] FIG. 3 is an end view of the cutting insert shown in FIG. 1;

[0035] FIG. 4a is a cross-sectional view of the cutting insert shown in FIG. 2a, taken along the line IVa-IVa;

[0036] FIG. 4b is a cross-sectional view of the cutting insert shown in FIG. 2a, taken along the line IVb-IVb;

[0037] FIG. 5 is a cross-sectional view of the cutting insert shown in FIG. 2a, taken along the line V-V;

[0038] FIG. 6 is a perspective view of a tool holder in accordance with some embodiments of the present invention;

[0039] FIG. 7 is a first side view of the tool holder shown in FIG. 6;

[0040] FIG. 8 is a first side view of a cutting tool in accordance with some embodiments of the present invention;

[0041] FIG. 9 is a second side view of the cutting tool shown in FIG. 8;

[0042] FIG. 10 is an end view of the cutting tool shown in FIG. 8;

[0043] FIG. 11a is a cross-sectional view of the cutting tool shown in FIG. 8, taken along the line XIa-XIa; and

[0044] FIG. 11b is a cross-sectional view of the cutting tool shown in FIG. 8, taken along the line XIb-XIb.

DETAILED DESCRIPTION OF THE INVENTION

[0045] A first aspect of the present invention relates to blade-shaped cutting insert 20, having opposing first and second insert side surfaces 22a, 22b with a peripheral surface 24 extending therebetween.

[0046] In some embodiments of the present invention, the cutting insert 20 may preferably be manufactured by form pressing and sintering a cemented carbide, such as tungsten carbide, and may be coated or uncoated.

[0047] The various features of cutting insert 20 are shown in proportion to one another in FIGS. 1 to 3, except for unavoidable inaccuracies due to copying, etc.

[0048] As shown in FIGS. 1 to 3, the peripheral surface 24 includes first and second diverging flank surfaces 26a, 26b and an upper surface 28, and the first and second diverging flank surfaces 26a, 26b are bisected by a first plane P1 (vertical insert plane) transverse to the upper surface 28.

[0049] In some embodiments of the present invention, as shown in FIG. 2a, the first and second diverging flank surfaces 26a, 26b may form an acute internal first angle 1.

[0050] Also in some embodiments of the present invention, the first angle 1 may have a value of between 30 and 80 degrees.

[0051] Further in some embodiments of the present invention, the first and second diverging flank surfaces 26a, 26b may be spaced apart by an intermediate surface 30. The vertical insert plane P1 may bisect the intermediate surface 30.

[0052] It should be appreciated that use of the terms internal angle and external angle throughout the description and claims refers to an angle between two planar surface components of a pair of surfaces as measured internal and external to the member on which the two surface components are formed, respectively.

[0053] As shown in FIGS. 4a and 4b, in cross-sections taken in second and third planes P2, P3 transverse to the vertical insert plane P1, the first and second flank surfaces 26a, 26b may be respectively V-shaped.

[0054] In some embodiments of the present invention, as shown in FIGS. 4a and 4b, in the cross-sections taken in the second and third planes P2, P3, the first and second flank surfaces 26a, 26b may be respectively convex.

[0055] It should be appreciated that for embodiments of the present invention that the first and second flank surfaces 26a, 26b are convex, as opposed to concave, form pressing of the cutting insert 20 can be performed with greater ease and efficiency.

[0056] In some embodiments of the present invention, the first flank surface 26a may have two parallely extending first flank sub-surfaces 32a, 32b, and the second flank surface 26b may have two parallely extending second flank sub-surfaces 88a, 88b.

[0057] Also in some embodiments of the present invention, as shown in FIGS. 4a and 4b, in the cross-sections taken in the second and third planes P2, P3, the two first and two second flank sub-surfaces (32a, 32b; 88a, 88b) may respectively form obtuse internal second and third angles 2, 3.

[0058] As shown in FIGS. 2b and 3, the cutting insert 20 has a first cutting portion 34a with a first primary cutting edge 36a extending between the first and second insert side surfaces 22a, 22b, defining a maximum insert width W.sub.MAX of the cutting insert 20.

[0059] In some embodiments of the present invention, the maximum insert width W.sub.MAX may be less than 1.5 mm.

[0060] It should be appreciated that having a very narrow maximum insert width W.sub.MAX of less than 1.5 mm enables the cutting insert 20 to perform parting operations with reduced waste of the workpiece material.

[0061] In some embodiments of the present invention, the cutting insert 20 may exhibit mirror symmetry about a fourth plane P4 (longitudinal insert plane) located midway between the first and second insert side surfaces 22a, 22b and intersecting the first primary cutting edge 36a.

[0062] As shown in FIGS. 2a and 2b, the cutting insert 20 has a maximum insert length L.sub.MAX measured perpendicular to the vertical insert plane P1, and in FIGS. 2a and 3, the cutting insert 20 has a maximum insert height H.sub.MAX measured parallel to the vertical insert plane P1.

[0063] According to the present invention, the maximum insert length L.sub.MAX is at least twelve times greater than the maximum insert width W.sub.MAX, and the maximum insert height H.sub.MAX is at least eight times greater than the maximum insert width W.sub.MAX.

[0064] In some embodiments of the present invention, the maximum insert height H.sub.MAX may be measured between the upper surface 28 and the intermediate surface 30.

[0065] Also in some embodiments of the present invention, and as can be seen from the proportional drawing of FIG. 2b, the maximum insert length L.sub.MAX may be more than sixteen times greater than the maximum insert width W.sub.MAX.

[0066] Further in some embodiments of the present invention, and as can be seen from the proportional drawing of FIG. 3, the maximum insert height H.sub.MAX may be more than ten times greater than the maximum insert width W.sub.MAX.

[0067] As shown in FIGS. 1 to 3, the first primary cutting edge 36a may be formed at the intersection of a first rake surface 38a and a first relief surface 40a, with the first rake surface 38a disposed on the upper surface 28, and the first relief surface 40a spaced apart from the first flank surface 26a by a first lower surface 42a. As seen in FIG. 2a, the first lower surface 42a may form a step between the first relief surface 40a and the first flank surface 26a.

[0068] In some embodiments of the present invention, as shown in FIG. 2a, the first lower surface 42a may form an obtuse external fourth angle 4 with the first flank surface 26a.

[0069] Also in some embodiments of the present invention, the fourth angle 4 may have a value of between 135 and 160 degrees.

[0070] Further in some embodiments of the present invention, the peripheral surface 24 may include a curved transitional surface 44 extending between the first flank surface 26a and the first lower surface 42a.

[0071] Yet further in some embodiments of the present invention, as shown in FIG. 2a, the first relief surface 40a may form an acute fifth angle 5 with the vertical insert plane P1, and the fifth angle 5 may be equal to or less than 10 degrees.

[0072] As shown in FIG. 2a, the cutting insert 20 may exhibit mirror symmetry about the vertical insert plane P1, and include a second cutting portion 34b having a second primary cutting edge 36b. As compared to the elongated holder blade seen in aforementioned US201540063929A1 discussed above, cutting insert 20 is devoid of insert receiving pockets.

[0073] In some embodiments of the present invention, the maximum insert length L.sub.MAX may be measured between the first and second primary cutting edges 36a, 36b.

[0074] Also in some embodiments of the present invention, the second primary cutting edge 36b may be formed at the intersection of a second rake surface 38b and a second relief surface 40b, with the second rake surface 38b disposed on the upper surface 28, and the second relief surface 40b spaced apart from the second flank surface 26b by a second lower surface 42b.

[0075] As shown in FIG. 2a, a fastening portion 84 of the upper surface 28 intersecting the vertical insert plane P1 may face in an upward direction D.sub.U.

[0076] In some embodiments of the present invention, the first and second flank surfaces 26a, 26b may diverge away from each other in the upward direction D.sub.U, i.e., in a direction away from the intermediate surface 30.

[0077] As shown in FIG. 2a, the first lower surface 42a may face in a downward direction D.sub.D opposite to the upward direction D.sub.U.

[0078] In some embodiments of the present invention, the first lower surface 42a may be parallel to the fastening portion 84.

[0079] Also in some embodiments of the present invention, the first lower surface 42a may be perpendicular to the vertical insert plane P1.

[0080] Further in some embodiments of the present invention, the first primary cutting edge 36a may be located a maximum first height H1 above the first lower surface 42a when measured parallel to the vertical insert plane P1, and the maximum first height H1 may be less than two-thirds the maximum insert height H.sub.MAX.

[0081] As shown in FIG. 5, in a cross-section taken in a fifth plane P5 parallel to the vertical insert plane P1, the first lower surface 42a may be V-shaped.

[0082] In some embodiments of the present invention, as shown in FIG. 5, in the cross-section taken in the fifth plane P5, the first lower surface 42a may be convex.

[0083] It should be appreciated that for embodiments of the present invention in which the first lower surface 42a is convex, as opposed to concave, form pressing of the cutting insert 20 can be performed with greater ease and efficiency.

[0084] Also in some embodiments of the present invention, the first lower surface 42a may have two parallely extending first lower sub-surfaces 46a, 46b, and as shown in FIG. 5, in the cross-section taken in the fifth plane P5, the two first lower sub-surfaces 46a, 46b may form an obtuse internal sixth angle 6.

[0085] As shown in FIGS. 6 to 10, a second aspect of the present invention relates to a cutting tool 48 comprising a tool holder 50 and the cutting insert 20 removably secured in an insert receiving pocket 52 of the tool holder 50.

[0086] The various features seen in the tool holder 50 of FIGS. 6 and 7 are shown in proportion to one another, except for unavoidable inaccuracies due to copying, etc.

[0087] In some embodiments of the present invention, the tool holder 50 may preferably be manufactured from tool steel.

[0088] Also in some embodiments of the present invention, as shown in FIGS. 6 and 7, a tool shank 54 may extend rearwardly from the insert receiving pocket 52.

[0089] As shown in FIGS. 8 to 10, the first primary cutting edge 36a is operative and has first and second lateral end points N1, N2 contained in opposing first and second circular sides S.sub.D1, S.sub.D2, respectively, of an imaginary disc DI.

[0090] It should be appreciated that the first and second circular sides S.sub.D1, S.sub.D2 are spaced apart by a distance equal to the maximum insert width W.sub.MAX, which is therefore also the thickness of the imaginary disc DI.

[0091] The imaginary disc DI has a central disc axis A1 containing at least one of the first and second lateral end points N1, N2 and a first diameter d1 equal to the maximum insert length L.sub.MAX.

[0092] In some embodiments of the present invention, including embodiments in which the cutting insert 20 exhibits mirror symmetry about the longitudinal insert plane P4, the central disc axis A1 may contain both of the first and second lateral end points N1, N2.

[0093] Also in some embodiments of the present invention, first and second imaginary lines L1, L2 parallel to the central disc axis A1 and extending laterally outwardly from any respective points on the first and second circular sides S.sub.D1, S.sub.D2, may not intersect any portion of the tool holder 50.

[0094] It should be appreciated that in some embodiments of the present invention, as shown in FIG. 9, the cutting tool 48 may have a cutting depth Dc greater than the radius of the imaginary disc DI, and thus greater than half the maximum insert length L.sub.MAX.

[0095] It should also be appreciated that by virtue of the cutting insert 20 being manufactured from cemented carbide, which has a greater value of Young's modulus than the tool steel from which the tool holder 50 may be manufactured, and also having high relative values of maximum insert length L.sub.MAX and maximum insert height H.sub.MAX, the cutting tool 48 is advantageously provided with a high level of rigidity in the cutting region.

[0096] As shown in FIGS. 6 and 7, the insert receiving pocket 52 opens out to a forward end 56 of the tool holder 50 and is defined by an upper clamping jaw 58 and a lower clamping jaw 60.

[0097] In some embodiments of the present invention, the upper and lower clamping jaws 58, 60 may also be spaced apart by a clamping slot 62.

[0098] Also in some embodiments of the present invention, the upper clamping jaw 58 may be resiliently displaceable relative to the lower clamping jaw 60.

[0099] Further in some embodiments of the present invention, each of the upper and lower clamping jaws 58, 60 may have a through hole 90.

[0100] Each through hole 90 may be adapted to receive a respective member of an actuating key (not shown), which serves to facilitate insertion and removal of the cutting insert 20 into and out of the insert receiving pocket 52.

[0101] As shown in FIG. 7, in a side view of the tool holder 50, the insert receiving pocket 52 may include first and second diverging abutment surfaces 64a, 64b bisected by a vertical pocket plane P.sub.V.

[0102] In some embodiments of the present invention, the first and second abutment surfaces 64a, 64b may be disposed on the lower clamping jaw 60.

[0103] Also in some embodiments of the present invention, as shown in FIG. 7, the first and second abutment surfaces 64a, 64b may form an acute external seventh angle 7.

[0104] Further in some embodiments of the present invention, the seventh angle 7 may have a value of between 30 and 80 degrees.

[0105] Yet further in some embodiments of the present invention, the first and second abutment surfaces 64a, 64b may exhibit mirror symmetry about the vertical pocket plane P.sub.V.

[0106] As shown in FIGS. 8 and 9, a portion of the first flank surface 26a may be in contact with the first abutment surface 64a and a portion of the second flank surface 26b may be in contact with the second abutment surface 64b.

[0107] In some embodiments of the present invention, the vertical insert plane P1 and the vertical pocket plane P.sub.V may be coplanar.

[0108] Also in some embodiments of the present invention, the first and second flank surfaces 26a, 26b may respectively include first and second non-contacting flank portions 92a, 92b which do not make contact with the lower clamping jaw 60.

[0109] The first and second non-contacting flank portions 92a, 92b may be located closer to the first and second lower surfaces 42a, 42b, respectively, than the above-mentioned portions of the first and second flank surfaces 26a, 26b which do make contact with the first and second abutment surfaces 64a, 64b.

[0110] It should be appreciated that the first and second abutment surfaces 64a, 64b may be located outside the space defined by the imaginary disc DI.

[0111] It should be also appreciated that in some embodiments of the present invention, only one of the two first flank sub-surfaces 32a, 32b of the first flank surface 26a may be in contact with the first abutment surface 64a, and only one of the two second flank sub-surfaces 34a, 34b of the second flank surface 26b may be in contact with the second abutment surface 64b.

[0112] It should be further appreciated that for embodiments of the present invention, in which the cutting insert 20 has two cutting portions 34a, 34b, and the second primary cutting edge 36b is operative (not shown), a portion of the first flank surface 26a may be in contact with the second abutment surface 64b and a portion of the second flank surface 26b may be in contact with the first abutment surface 64a.

[0113] As shown in FIGS. 8 and 10, a third imaginary line L3 parallel to the central disc axis A1 and extending laterally inwardly from a point on the first or second circular side S.sub.D1, S.sub.D2 may intersect a front support portion 66 of the lower clamping jaw 60.

[0114] As shown in FIGS. 8 to 10, the cutting insert's first lower surface 42a may be in contact with a front support surface 68 on the front support portion 66 of the lower clamping jaw 60.

[0115] It should be appreciated that locating the front support surface 68 within the space defined by the imaginary disc DI provides additional support to the cutting insert 20 via the first lower surface 42a, and also improved accuracy by virtue of the close proximity of the lower surface 42a to the operative first primary cutting edge 36a.

[0116] In some embodiments of the present invention, the first lower surface 42a may be located forward of the vertical pocket plane P.sub.V.

[0117] For embodiments of the present invention that the first lower surface 42a is V-shaped in the cross-section taken in the fifth plane P5, the front support surface 68 may be correspondingly V-shaped.

[0118] It should be appreciated that for embodiments of the present invention, in which the cutting insert 20 has two cutting portions 34a, 34b, and the second primary cutting edge 36b is operative (not shown), the second lower surface 42b may be in contact with the front support surface 68 and located forward of the vertical pocket plane P.sub.V.

[0119] As shown in FIG. 10, the lower clamping jaw 60 may have opposing first and second lower jaw side surfaces 70a, 70b, and the first and second lower jaw side surfaces 70a, 70b may define a lower jaw thickness T.

[0120] In some embodiments of the present invention, the lower jaw thickness T may be more than twice the maximum insert width W.sub.MAX, thus advantageously contributing to the rigidity of the cutting tool 48.

[0121] Also in some embodiments of the present invention, the lower jaw thickness T may be less than five times the maximum insert width W.sub.MAX, thus providing an advantageously narrow blade-shaped cutting tool 48.

[0122] Further in some embodiments of the present invention, the first and second lower jaw side surfaces 70a, 70b may be parallel.

[0123] As shown in FIGS. 11a and 11b, in cross-sections taken in sixth and seventh planes P6, P7 transverse to the vertical pocket plane P.sub.V, respectively, the first abutment surface 64a may form an acute internal eighth angle 8, with the first lower jaw side surface 70a, and the second abutment surface 64b may form an acute internal ninth angle 9, with the first lower jaw side surface 70a.

[0124] In some embodiments of the present invention, the eighth angle 8 may be equal to the ninth angle 9.

[0125] As shown in FIGS. 6 and 7, the lower clamping jaw 60 may be divided into a front lower jaw 72 and a rear lower jaw 74 by a lower slot 76.

[0126] In some embodiments of the present invention, the front lower jaw 72 may be resiliently displaceable relative to the rear lower jaw 74.

[0127] Also in some embodiments of the present invention, the front support portion 66 may be disposed on the front lower jaw 72, and the second abutment surface 64b may be disposed on the rear lower jaw 74.

[0128] Further in some embodiments of the present invention, the first abutment surface 64a may be disposed on the front lower jaw 72.

[0129] It should be appreciated that provision of the lower slot 76 advantageously ensures simultaneous and reliable contact between the cutting insert's first and second flank surfaces 26a, 26b and the tool holder's first and second abutment surfaces 64a, 64b, as well as between the first or second lower surface 42a, 42b and the front support surface 68, thus avoiding an over-constrained configuration.

[0130] As shown in FIG. 9, the central disc axis A1 contains the center point N.sub.C of an imaginary circle C coplanar with one of the first and second circular sides S.sub.D1, S.sub.D2, and the imaginary circle C has a second diameter d2 greater than the maximum insert length L.sub.MAX and less than twice the maximum insert length L.sub.MAX.

[0131] In some embodiments of the present invention, as shown in FIG. 9, a first arc portion R.sub.C of the imaginary circle C may intersect a lateral support portion 78 of the lower clamping jaw 60.

[0132] Also in some embodiments of the present invention, the first arc portion R.sub.C may be continuous and subtend an angle of greater than 25 degrees.

[0133] Further in some embodiments of the present invention, the first arc portion R.sub.C may be disposed on the rear lower jaw 74.

[0134] As shown in FIG. 10, one of first and second insert side surfaces 22a, 22b may be in contact with a lateral support surface 80 on the lateral support portion 78 of the lower clamping jaw 60.

[0135] It should be appreciated that the lateral support portion 78 contributes to the rigidity of the cutting tool 48.

[0136] It should also be appreciated that the lateral support surface 80, in addition to providing lateral support to the cutting insert 20, acts as a locating reference surface, aiding quick and efficient insertion of the cutting insert 20 into the insert receiving pocket 52 during assembly of the cutting tool 48.

[0137] In some embodiments of the present invention, the first and second abutment surfaces 64a, 64b may be located adjacent respective portions of the lateral support surface 80.

[0138] Also in some embodiments of the present invention, as shown in FIGS. 11a and 11b, the first abutment surface 64a may form an acute external tenth angle 10 with the lateral support surface 80, and the second abutment surface 64b may form an acute external eleventh angle 11 with the lateral support surface 80.

[0139] Further in some embodiments of the present invention, the tenth angle 10 may be equal to the eleventh angle 11.

[0140] It should be appreciated that for embodiments of the present invention in which the first and second abutment surfaces 64a, 64b form acute external angles with the lateral support surface 80, the insert receiving pocket 52 is advantageously provided with a dovetail-type configuration, and the cutting insert 20 is reliably secured therein.

[0141] In some embodiments of the present invention, the lateral support surface 80 may be parallel to the first lower jaw side surface 70a.

[0142] As shown in FIGS. 8 to 10, the upper clamping jaw 58 may have a clamping surface 82, and the clamping surface 82 may be in contact with the cutting insert's fastening portion 84 on the upper surface 28.

[0143] In some embodiments of the present invention, as shown in FIG. 2a, the cutting insert 20 may be divided into three equi-length segments S.sub.G1, S.sub.G2, S.sub.G3 along the maximum insert length L.sub.MAX, and the fastening portion 84 may be located on the middle segment S.sub.G2 of the three equi-length segments S.sub.G1, S.sub.G2, S.sub.G3.

[0144] Also in some embodiments of the present invention, a rear non-abutting portion 86 of the cutting insert's peripheral surface 24 which is not associated with the operative first primary cutting edge 36a may circumferentially extend from the fastening portion 84 to the second flank surface 26b. In such case, the entire rear non-abutting portion 86 may not be in contact with the tool holder 50.

[0145] Further in some embodiments of the present invention, the rear non-abutting portion 86 may include the second rake surface 38b, the second relief surface 40b, and the second lower surface 42b.

[0146] Yet further in some embodiments of the present invention, the fastening portion 84 may intersect the vertical insert plane P1.

[0147] It should be appreciated that for embodiments of the present invention, in which the cutting insert 20 has two cutting portions 34a, 34b, and the second primary cutting edge 36b is operative (not shown), the rear non-abutting portion 86 may circumferentially extend from the fastening portion 84 to the first flank surface 26a, and not include the second primary cutting edge 36b.

[0148] Although the present invention has been described to a certain degree of particularity, it should be understood that various alterations and modifications could be made without departing from the spirit or scope of the invention as hereinafter claimed.